We also have a 30 amp trailer.
In 6 years of camping we have never popped either the 30 amp main
in my trailer or the 30 amp on the power post.
We leave the WH on electric. We have a micro wave and a toaster
and a coffee pot and roof AC. We use a space heater in cold weather.
Sure if I turned them all on at once I could pop a breaker.
Typically the AC is not running during breakfast.
Don't be too worried about tripping the main unless you know you've
done it before. We never have.

If all WH valves are in winter mode the tank is probably empty and
the electric element is probably fried. I hope not!

Thanks to everyone that responded. My water heater doesn't look like the one in the picture Fonzie sent but it showed me where the problem was. The dealer winterized the Solera R for me while it was there for some warranty work. When I dewinterized it I didn't pay attention to the third valve coming out of the water heater due to its location (very hard to see). I just needed to turn the valve open. Duh! Learning something everyday.

Can't really get a picture of mine (Sunseeker) but here is a description: There is a pipe going into the water heater and another going out (top and bottom of the rear of WH). For "summer" thoses valve need to be turned parallel to the pipe (open). There is a pipe that connects the in and out of the WH (the "bypass"). The valve in the middle of that pipe needs to be closed--perpendicular to the pipe.